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<li class="navelem"><a class="el" href="dir_5956a3e80a20e8e03eb577bedb92689f.html">gpu</a></li><li class="navelem"><a class="el" href="dir_5865795754b604b902e524ed1add5694.html">utils</a></li>  </ul>
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<div class="title">MergeNetworkBlock.cuh</div>  </div>
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<div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno">    1</span>&#160;<span class="comment">/**</span></div>
<div class="line"><a name="l00002"></a><span class="lineno">    2</span>&#160;<span class="comment"> * Copyright (c) Facebook, Inc. and its affiliates.</span></div>
<div class="line"><a name="l00003"></a><span class="lineno">    3</span>&#160;<span class="comment"> *</span></div>
<div class="line"><a name="l00004"></a><span class="lineno">    4</span>&#160;<span class="comment"> * This source code is licensed under the MIT license found in the</span></div>
<div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;<span class="comment"> * LICENSE file in the root directory of this source tree.</span></div>
<div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;<span class="comment"> */</span></div>
<div class="line"><a name="l00007"></a><span class="lineno">    7</span>&#160;</div>
<div class="line"><a name="l00008"></a><span class="lineno">    8</span>&#160;<span class="preprocessor">#pragma once</span></div>
<div class="line"><a name="l00009"></a><span class="lineno">    9</span>&#160;<span class="preprocessor"></span></div>
<div class="line"><a name="l00010"></a><span class="lineno">   10</span>&#160;<span class="preprocessor">#include &quot;DeviceDefs.cuh&quot;</span></div>
<div class="line"><a name="l00011"></a><span class="lineno">   11</span>&#160;<span class="preprocessor">#include &quot;MergeNetworkUtils.cuh&quot;</span></div>
<div class="line"><a name="l00012"></a><span class="lineno">   12</span>&#160;<span class="preprocessor">#include &quot;PtxUtils.cuh&quot;</span></div>
<div class="line"><a name="l00013"></a><span class="lineno">   13</span>&#160;<span class="preprocessor">#include &quot;StaticUtils.h&quot;</span></div>
<div class="line"><a name="l00014"></a><span class="lineno">   14</span>&#160;<span class="preprocessor">#include &quot;WarpShuffles.cuh&quot;</span></div>
<div class="line"><a name="l00015"></a><span class="lineno">   15</span>&#160;<span class="preprocessor">#include &quot;../../FaissAssert.h&quot;</span></div>
<div class="line"><a name="l00016"></a><span class="lineno">   16</span>&#160;<span class="preprocessor">#include &lt;cuda.h&gt;</span></div>
<div class="line"><a name="l00017"></a><span class="lineno">   17</span>&#160;</div>
<div class="line"><a name="l00018"></a><span class="lineno">   18</span>&#160;<span class="keyword">namespace </span>faiss { <span class="keyword">namespace </span>gpu {</div>
<div class="line"><a name="l00019"></a><span class="lineno">   19</span>&#160;</div>
<div class="line"><a name="l00020"></a><span class="lineno">   20</span>&#160;<span class="comment">// Merge pairs of lists smaller than blockDim.x (NumThreads)</span></div>
<div class="line"><a name="l00021"></a><span class="lineno">   21</span>&#160;<span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00022"></a><span class="lineno">   22</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00023"></a><span class="lineno">   23</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00024"></a><span class="lineno">   24</span>&#160;          <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00025"></a><span class="lineno">   25</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00026"></a><span class="lineno">   26</span>&#160;          <span class="keywordtype">bool</span> AllThreads,</div>
<div class="line"><a name="l00027"></a><span class="lineno">   27</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00028"></a><span class="lineno">   28</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00029"></a><span class="lineno">   29</span>&#160;          <span class="keywordtype">bool</span> FullMerge&gt;</div>
<div class="line"><a name="l00030"></a><span class="lineno">   30</span>&#160;<span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> blockMergeSmall(K* listK, V* listV) {</div>
<div class="line"><a name="l00031"></a><span class="lineno">   31</span>&#160;  static_assert(utils::isPowerOf2(L), <span class="stringliteral">&quot;L must be a power-of-2&quot;</span>);</div>
<div class="line"><a name="l00032"></a><span class="lineno">   32</span>&#160;  static_assert(utils::isPowerOf2(NumThreads),</div>
<div class="line"><a name="l00033"></a><span class="lineno">   33</span>&#160;                <span class="stringliteral">&quot;NumThreads must be a power-of-2&quot;</span>);</div>
<div class="line"><a name="l00034"></a><span class="lineno">   34</span>&#160;  static_assert(L &lt;= NumThreads, <span class="stringliteral">&quot;merge list size must be &lt;= NumThreads&quot;</span>);</div>
<div class="line"><a name="l00035"></a><span class="lineno">   35</span>&#160;</div>
<div class="line"><a name="l00036"></a><span class="lineno">   36</span>&#160;  <span class="comment">// Which pair of lists we are merging</span></div>
<div class="line"><a name="l00037"></a><span class="lineno">   37</span>&#160;  <span class="keywordtype">int</span> mergeId = threadIdx.x / L;</div>
<div class="line"><a name="l00038"></a><span class="lineno">   38</span>&#160;</div>
<div class="line"><a name="l00039"></a><span class="lineno">   39</span>&#160;  <span class="comment">// Which thread we are within the merge</span></div>
<div class="line"><a name="l00040"></a><span class="lineno">   40</span>&#160;  <span class="keywordtype">int</span> tid = threadIdx.x % L;</div>
<div class="line"><a name="l00041"></a><span class="lineno">   41</span>&#160;</div>
<div class="line"><a name="l00042"></a><span class="lineno">   42</span>&#160;  <span class="comment">// listK points to a region of size N * 2 * L</span></div>
<div class="line"><a name="l00043"></a><span class="lineno">   43</span>&#160;  listK += 2 * L * mergeId;</div>
<div class="line"><a name="l00044"></a><span class="lineno">   44</span>&#160;  listV += 2 * L * mergeId;</div>
<div class="line"><a name="l00045"></a><span class="lineno">   45</span>&#160;</div>
<div class="line"><a name="l00046"></a><span class="lineno">   46</span>&#160;  <span class="comment">// It&#39;s not a bitonic merge, both lists are in the same direction,</span></div>
<div class="line"><a name="l00047"></a><span class="lineno">   47</span>&#160;  <span class="comment">// so handle the first swap assuming the second list is reversed</span></div>
<div class="line"><a name="l00048"></a><span class="lineno">   48</span>&#160;  <span class="keywordtype">int</span> pos = L - 1 - tid;</div>
<div class="line"><a name="l00049"></a><span class="lineno">   49</span>&#160;  <span class="keywordtype">int</span> stride = 2 * tid + 1;</div>
<div class="line"><a name="l00050"></a><span class="lineno">   50</span>&#160;</div>
<div class="line"><a name="l00051"></a><span class="lineno">   51</span>&#160;  <span class="keywordflow">if</span> (AllThreads || (threadIdx.x &lt; N * L)) {</div>
<div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;    K ka = listK[pos];</div>
<div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;    K kb = listK[pos + stride];</div>
<div class="line"><a name="l00054"></a><span class="lineno">   54</span>&#160;</div>
<div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;    <span class="keywordtype">bool</span> swap = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;    listK[pos] = swap ? kb : ka;</div>
<div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;    listK[pos + stride] = swap ? ka : kb;</div>
<div class="line"><a name="l00058"></a><span class="lineno">   58</span>&#160;</div>
<div class="line"><a name="l00059"></a><span class="lineno">   59</span>&#160;    V va = listV[pos];</div>
<div class="line"><a name="l00060"></a><span class="lineno">   60</span>&#160;    V vb = listV[pos + stride];</div>
<div class="line"><a name="l00061"></a><span class="lineno">   61</span>&#160;    listV[pos] = swap ? vb : va;</div>
<div class="line"><a name="l00062"></a><span class="lineno">   62</span>&#160;    listV[pos + stride] = swap ? va : vb;</div>
<div class="line"><a name="l00063"></a><span class="lineno">   63</span>&#160;</div>
<div class="line"><a name="l00064"></a><span class="lineno">   64</span>&#160;    <span class="comment">// FIXME: is this a CUDA 9 compiler bug?</span></div>
<div class="line"><a name="l00065"></a><span class="lineno">   65</span>&#160;    <span class="comment">// K&amp; ka = listK[pos];</span></div>
<div class="line"><a name="l00066"></a><span class="lineno">   66</span>&#160;    <span class="comment">// K&amp; kb = listK[pos + stride];</span></div>
<div class="line"><a name="l00067"></a><span class="lineno">   67</span>&#160;</div>
<div class="line"><a name="l00068"></a><span class="lineno">   68</span>&#160;    <span class="comment">// bool s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</span></div>
<div class="line"><a name="l00069"></a><span class="lineno">   69</span>&#160;    <span class="comment">// swap(s, ka, kb);</span></div>
<div class="line"><a name="l00070"></a><span class="lineno">   70</span>&#160;</div>
<div class="line"><a name="l00071"></a><span class="lineno">   71</span>&#160;    <span class="comment">// V&amp; va = listV[pos];</span></div>
<div class="line"><a name="l00072"></a><span class="lineno">   72</span>&#160;    <span class="comment">// V&amp; vb = listV[pos + stride];</span></div>
<div class="line"><a name="l00073"></a><span class="lineno">   73</span>&#160;    <span class="comment">// swap(s, va, vb);</span></div>
<div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;  }</div>
<div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;</div>
<div class="line"><a name="l00076"></a><span class="lineno">   76</span>&#160;  __syncthreads();</div>
<div class="line"><a name="l00077"></a><span class="lineno">   77</span>&#160;</div>
<div class="line"><a name="l00078"></a><span class="lineno">   78</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00079"></a><span class="lineno">   79</span>&#160;<span class="preprocessor"></span>  <span class="keywordflow">for</span> (<span class="keywordtype">int</span> stride = L / 2; stride &gt; 0; stride /= 2) {</div>
<div class="line"><a name="l00080"></a><span class="lineno">   80</span>&#160;    <span class="keywordtype">int</span> pos = 2 * tid - (tid &amp; (stride - 1));</div>
<div class="line"><a name="l00081"></a><span class="lineno">   81</span>&#160;</div>
<div class="line"><a name="l00082"></a><span class="lineno">   82</span>&#160;    <span class="keywordflow">if</span> (AllThreads || (threadIdx.x &lt; N * L)) {</div>
<div class="line"><a name="l00083"></a><span class="lineno">   83</span>&#160;      K ka = listK[pos];</div>
<div class="line"><a name="l00084"></a><span class="lineno">   84</span>&#160;      K kb = listK[pos + stride];</div>
<div class="line"><a name="l00085"></a><span class="lineno">   85</span>&#160;</div>
<div class="line"><a name="l00086"></a><span class="lineno">   86</span>&#160;      <span class="keywordtype">bool</span> swap = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00087"></a><span class="lineno">   87</span>&#160;      listK[pos] = swap ? kb : ka;</div>
<div class="line"><a name="l00088"></a><span class="lineno">   88</span>&#160;      listK[pos + stride] = swap ? ka : kb;</div>
<div class="line"><a name="l00089"></a><span class="lineno">   89</span>&#160;</div>
<div class="line"><a name="l00090"></a><span class="lineno">   90</span>&#160;      V va = listV[pos];</div>
<div class="line"><a name="l00091"></a><span class="lineno">   91</span>&#160;      V vb = listV[pos + stride];</div>
<div class="line"><a name="l00092"></a><span class="lineno">   92</span>&#160;      listV[pos] = swap ? vb : va;</div>
<div class="line"><a name="l00093"></a><span class="lineno">   93</span>&#160;      listV[pos + stride] = swap ? va : vb;</div>
<div class="line"><a name="l00094"></a><span class="lineno">   94</span>&#160;</div>
<div class="line"><a name="l00095"></a><span class="lineno">   95</span>&#160;      <span class="comment">// FIXME: is this a CUDA 9 compiler bug?</span></div>
<div class="line"><a name="l00096"></a><span class="lineno">   96</span>&#160;      <span class="comment">// K&amp; ka = listK[pos];</span></div>
<div class="line"><a name="l00097"></a><span class="lineno">   97</span>&#160;      <span class="comment">// K&amp; kb = listK[pos + stride];</span></div>
<div class="line"><a name="l00098"></a><span class="lineno">   98</span>&#160;</div>
<div class="line"><a name="l00099"></a><span class="lineno">   99</span>&#160;      <span class="comment">// bool s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</span></div>
<div class="line"><a name="l00100"></a><span class="lineno">  100</span>&#160;      <span class="comment">// swap(s, ka, kb);</span></div>
<div class="line"><a name="l00101"></a><span class="lineno">  101</span>&#160;</div>
<div class="line"><a name="l00102"></a><span class="lineno">  102</span>&#160;      <span class="comment">// V&amp; va = listV[pos];</span></div>
<div class="line"><a name="l00103"></a><span class="lineno">  103</span>&#160;      <span class="comment">// V&amp; vb = listV[pos + stride];</span></div>
<div class="line"><a name="l00104"></a><span class="lineno">  104</span>&#160;      <span class="comment">// swap(s, va, vb);</span></div>
<div class="line"><a name="l00105"></a><span class="lineno">  105</span>&#160;    }</div>
<div class="line"><a name="l00106"></a><span class="lineno">  106</span>&#160;</div>
<div class="line"><a name="l00107"></a><span class="lineno">  107</span>&#160;    __syncthreads();</div>
<div class="line"><a name="l00108"></a><span class="lineno">  108</span>&#160;  }</div>
<div class="line"><a name="l00109"></a><span class="lineno">  109</span>&#160;}</div>
<div class="line"><a name="l00110"></a><span class="lineno">  110</span>&#160;</div>
<div class="line"><a name="l00111"></a><span class="lineno">  111</span>&#160;<span class="comment">// Merge pairs of sorted lists larger than blockDim.x (NumThreads)</span></div>
<div class="line"><a name="l00112"></a><span class="lineno">  112</span>&#160;<span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00113"></a><span class="lineno">  113</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00114"></a><span class="lineno">  114</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00115"></a><span class="lineno">  115</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00116"></a><span class="lineno">  116</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00117"></a><span class="lineno">  117</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00118"></a><span class="lineno">  118</span>&#160;          <span class="keywordtype">bool</span> FullMerge&gt;</div>
<div class="line"><a name="l00119"></a><span class="lineno">  119</span>&#160;<span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> blockMergeLarge(K* listK, V* listV) {</div>
<div class="line"><a name="l00120"></a><span class="lineno">  120</span>&#160;  static_assert(utils::isPowerOf2(L), <span class="stringliteral">&quot;L must be a power-of-2&quot;</span>);</div>
<div class="line"><a name="l00121"></a><span class="lineno">  121</span>&#160;  static_assert(L &gt;= kWarpSize, <span class="stringliteral">&quot;merge list size must be &gt;= 32&quot;</span>);</div>
<div class="line"><a name="l00122"></a><span class="lineno">  122</span>&#160;  static_assert(utils::isPowerOf2(NumThreads),</div>
<div class="line"><a name="l00123"></a><span class="lineno">  123</span>&#160;                <span class="stringliteral">&quot;NumThreads must be a power-of-2&quot;</span>);</div>
<div class="line"><a name="l00124"></a><span class="lineno">  124</span>&#160;  static_assert(L &gt;= NumThreads, <span class="stringliteral">&quot;merge list size must be &gt;= NumThreads&quot;</span>);</div>
<div class="line"><a name="l00125"></a><span class="lineno">  125</span>&#160;</div>
<div class="line"><a name="l00126"></a><span class="lineno">  126</span>&#160;  <span class="comment">// For L &gt; NumThreads, each thread has to perform more work</span></div>
<div class="line"><a name="l00127"></a><span class="lineno">  127</span>&#160;  <span class="comment">// per each stride.</span></div>
<div class="line"><a name="l00128"></a><span class="lineno">  128</span>&#160;  constexpr <span class="keywordtype">int</span> kLoopPerThread = L / NumThreads;</div>
<div class="line"><a name="l00129"></a><span class="lineno">  129</span>&#160;</div>
<div class="line"><a name="l00130"></a><span class="lineno">  130</span>&#160;  <span class="comment">// It&#39;s not a bitonic merge, both lists are in the same direction,</span></div>
<div class="line"><a name="l00131"></a><span class="lineno">  131</span>&#160;  <span class="comment">// so handle the first swap assuming the second list is reversed</span></div>
<div class="line"><a name="l00132"></a><span class="lineno">  132</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00133"></a><span class="lineno">  133</span>&#160;<span class="preprocessor"></span>  <span class="keywordflow">for</span> (<span class="keywordtype">int</span> loop = 0; loop &lt; kLoopPerThread; ++loop) {</div>
<div class="line"><a name="l00134"></a><span class="lineno">  134</span>&#160;    <span class="keywordtype">int</span> tid = loop * NumThreads + threadIdx.x;</div>
<div class="line"><a name="l00135"></a><span class="lineno">  135</span>&#160;    <span class="keywordtype">int</span> pos = L - 1 - tid;</div>
<div class="line"><a name="l00136"></a><span class="lineno">  136</span>&#160;    <span class="keywordtype">int</span> stride = 2 * tid + 1;</div>
<div class="line"><a name="l00137"></a><span class="lineno">  137</span>&#160;</div>
<div class="line"><a name="l00138"></a><span class="lineno">  138</span>&#160;   K ka = listK[pos];</div>
<div class="line"><a name="l00139"></a><span class="lineno">  139</span>&#160;    K kb = listK[pos + stride];</div>
<div class="line"><a name="l00140"></a><span class="lineno">  140</span>&#160;</div>
<div class="line"><a name="l00141"></a><span class="lineno">  141</span>&#160;    <span class="keywordtype">bool</span> swap = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00142"></a><span class="lineno">  142</span>&#160;    listK[pos] = swap ? kb : ka;</div>
<div class="line"><a name="l00143"></a><span class="lineno">  143</span>&#160;    listK[pos + stride] = swap ? ka : kb;</div>
<div class="line"><a name="l00144"></a><span class="lineno">  144</span>&#160;</div>
<div class="line"><a name="l00145"></a><span class="lineno">  145</span>&#160;    V va = listV[pos];</div>
<div class="line"><a name="l00146"></a><span class="lineno">  146</span>&#160;    V vb = listV[pos + stride];</div>
<div class="line"><a name="l00147"></a><span class="lineno">  147</span>&#160;    listV[pos] = swap ? vb : va;</div>
<div class="line"><a name="l00148"></a><span class="lineno">  148</span>&#160;    listV[pos + stride] = swap ? va : vb;</div>
<div class="line"><a name="l00149"></a><span class="lineno">  149</span>&#160;</div>
<div class="line"><a name="l00150"></a><span class="lineno">  150</span>&#160;    <span class="comment">// FIXME: is this a CUDA 9 compiler bug?</span></div>
<div class="line"><a name="l00151"></a><span class="lineno">  151</span>&#160;    <span class="comment">// K&amp; ka = listK[pos];</span></div>
<div class="line"><a name="l00152"></a><span class="lineno">  152</span>&#160;    <span class="comment">// K&amp; kb = listK[pos + stride];</span></div>
<div class="line"><a name="l00153"></a><span class="lineno">  153</span>&#160;</div>
<div class="line"><a name="l00154"></a><span class="lineno">  154</span>&#160;    <span class="comment">// bool s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</span></div>
<div class="line"><a name="l00155"></a><span class="lineno">  155</span>&#160;    <span class="comment">// swap(s, ka, kb);</span></div>
<div class="line"><a name="l00156"></a><span class="lineno">  156</span>&#160;</div>
<div class="line"><a name="l00157"></a><span class="lineno">  157</span>&#160;    <span class="comment">// V&amp; va = listV[pos];</span></div>
<div class="line"><a name="l00158"></a><span class="lineno">  158</span>&#160;    <span class="comment">// V&amp; vb = listV[pos + stride];</span></div>
<div class="line"><a name="l00159"></a><span class="lineno">  159</span>&#160;    <span class="comment">// swap(s, va, vb);</span></div>
<div class="line"><a name="l00160"></a><span class="lineno">  160</span>&#160;  }</div>
<div class="line"><a name="l00161"></a><span class="lineno">  161</span>&#160;</div>
<div class="line"><a name="l00162"></a><span class="lineno">  162</span>&#160;  __syncthreads();</div>
<div class="line"><a name="l00163"></a><span class="lineno">  163</span>&#160;</div>
<div class="line"><a name="l00164"></a><span class="lineno">  164</span>&#160;  constexpr <span class="keywordtype">int</span> kSecondLoopPerThread =</div>
<div class="line"><a name="l00165"></a><span class="lineno">  165</span>&#160;    FullMerge ? kLoopPerThread : kLoopPerThread / 2;</div>
<div class="line"><a name="l00166"></a><span class="lineno">  166</span>&#160;</div>
<div class="line"><a name="l00167"></a><span class="lineno">  167</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00168"></a><span class="lineno">  168</span>&#160;<span class="preprocessor"></span>  <span class="keywordflow">for</span> (<span class="keywordtype">int</span> stride = L / 2; stride &gt; 0; stride /= 2) {</div>
<div class="line"><a name="l00169"></a><span class="lineno">  169</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00170"></a><span class="lineno">  170</span>&#160;<span class="preprocessor"></span>    <span class="keywordflow">for</span> (<span class="keywordtype">int</span> loop = 0; loop &lt; kSecondLoopPerThread; ++loop) {</div>
<div class="line"><a name="l00171"></a><span class="lineno">  171</span>&#160;      <span class="keywordtype">int</span> tid = loop * NumThreads + threadIdx.x;</div>
<div class="line"><a name="l00172"></a><span class="lineno">  172</span>&#160;      <span class="keywordtype">int</span> pos = 2 * tid - (tid &amp; (stride - 1));</div>
<div class="line"><a name="l00173"></a><span class="lineno">  173</span>&#160;</div>
<div class="line"><a name="l00174"></a><span class="lineno">  174</span>&#160;      K ka = listK[pos];</div>
<div class="line"><a name="l00175"></a><span class="lineno">  175</span>&#160;      K kb = listK[pos + stride];</div>
<div class="line"><a name="l00176"></a><span class="lineno">  176</span>&#160;</div>
<div class="line"><a name="l00177"></a><span class="lineno">  177</span>&#160;      <span class="keywordtype">bool</span> swap = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</div>
<div class="line"><a name="l00178"></a><span class="lineno">  178</span>&#160;      listK[pos] = swap ? kb : ka;</div>
<div class="line"><a name="l00179"></a><span class="lineno">  179</span>&#160;      listK[pos + stride] = swap ? ka : kb;</div>
<div class="line"><a name="l00180"></a><span class="lineno">  180</span>&#160;</div>
<div class="line"><a name="l00181"></a><span class="lineno">  181</span>&#160;      V va = listV[pos];</div>
<div class="line"><a name="l00182"></a><span class="lineno">  182</span>&#160;      V vb = listV[pos + stride];</div>
<div class="line"><a name="l00183"></a><span class="lineno">  183</span>&#160;      listV[pos] = swap ? vb : va;</div>
<div class="line"><a name="l00184"></a><span class="lineno">  184</span>&#160;      listV[pos + stride] = swap ? va : vb;</div>
<div class="line"><a name="l00185"></a><span class="lineno">  185</span>&#160;</div>
<div class="line"><a name="l00186"></a><span class="lineno">  186</span>&#160;      <span class="comment">// FIXME: is this a CUDA 9 compiler bug?</span></div>
<div class="line"><a name="l00187"></a><span class="lineno">  187</span>&#160;      <span class="comment">// K&amp; ka = listK[pos];</span></div>
<div class="line"><a name="l00188"></a><span class="lineno">  188</span>&#160;      <span class="comment">// K&amp; kb = listK[pos + stride];</span></div>
<div class="line"><a name="l00189"></a><span class="lineno">  189</span>&#160;</div>
<div class="line"><a name="l00190"></a><span class="lineno">  190</span>&#160;      <span class="comment">// bool s = Dir ? Comp::gt(ka, kb) : Comp::lt(ka, kb);</span></div>
<div class="line"><a name="l00191"></a><span class="lineno">  191</span>&#160;      <span class="comment">// swap(s, ka, kb);</span></div>
<div class="line"><a name="l00192"></a><span class="lineno">  192</span>&#160;</div>
<div class="line"><a name="l00193"></a><span class="lineno">  193</span>&#160;      <span class="comment">// V&amp; va = listV[pos];</span></div>
<div class="line"><a name="l00194"></a><span class="lineno">  194</span>&#160;      <span class="comment">// V&amp; vb = listV[pos + stride];</span></div>
<div class="line"><a name="l00195"></a><span class="lineno">  195</span>&#160;      <span class="comment">// swap(s, va, vb);</span></div>
<div class="line"><a name="l00196"></a><span class="lineno">  196</span>&#160;    }</div>
<div class="line"><a name="l00197"></a><span class="lineno">  197</span>&#160;</div>
<div class="line"><a name="l00198"></a><span class="lineno">  198</span>&#160;    __syncthreads();</div>
<div class="line"><a name="l00199"></a><span class="lineno">  199</span>&#160;  }</div>
<div class="line"><a name="l00200"></a><span class="lineno">  200</span>&#160;}</div>
<div class="line"><a name="l00201"></a><span class="lineno">  201</span>&#160;<span class="comment"></span></div>
<div class="line"><a name="l00202"></a><span class="lineno">  202</span>&#160;<span class="comment">/// Class template to prevent static_assert from firing for</span></div>
<div class="line"><a name="l00203"></a><span class="lineno">  203</span>&#160;<span class="comment">/// mixing smaller/larger than block cases</span></div>
<div class="line"><a name="l00204"></a><span class="lineno">  204</span>&#160;<span class="comment"></span><span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00205"></a><span class="lineno">  205</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00206"></a><span class="lineno">  206</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00207"></a><span class="lineno">  207</span>&#160;          <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00208"></a><span class="lineno">  208</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00209"></a><span class="lineno">  209</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00210"></a><span class="lineno">  210</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00211"></a><span class="lineno">  211</span>&#160;          <span class="keywordtype">bool</span> SmallerThanBlock,</div>
<div class="line"><a name="l00212"></a><span class="lineno">  212</span>&#160;          <span class="keywordtype">bool</span> FullMerge&gt;</div>
<div class="line"><a name="l00213"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BlockMerge.html">  213</a></span>&#160;<span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BlockMerge.html">BlockMerge</a> {</div>
<div class="line"><a name="l00214"></a><span class="lineno">  214</span>&#160;};</div>
<div class="line"><a name="l00215"></a><span class="lineno">  215</span>&#160;<span class="comment"></span></div>
<div class="line"><a name="l00216"></a><span class="lineno">  216</span>&#160;<span class="comment">/// Merging lists smaller than a block</span></div>
<div class="line"><a name="l00217"></a><span class="lineno">  217</span>&#160;<span class="comment"></span><span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00218"></a><span class="lineno">  218</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00219"></a><span class="lineno">  219</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00220"></a><span class="lineno">  220</span>&#160;          <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00221"></a><span class="lineno">  221</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00222"></a><span class="lineno">  222</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00223"></a><span class="lineno">  223</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00224"></a><span class="lineno">  224</span>&#160;          <span class="keywordtype">bool</span> FullMerge&gt;</div>
<div class="line"><a name="l00225"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BlockMerge_3_01NumThreads_00_01K_00_01V_00_01N_00_01L_00_01Dir_00_01Comp_00_01true_00_01FullMerge_01_4.html">  225</a></span>&#160;<span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BlockMerge.html">BlockMerge</a>&lt;NumThreads, K, V, N, L, Dir, Comp, true, FullMerge&gt; {</div>
<div class="line"><a name="l00226"></a><span class="lineno">  226</span>&#160;  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K* listK, V* listV) {</div>
<div class="line"><a name="l00227"></a><span class="lineno">  227</span>&#160;    constexpr <span class="keywordtype">int</span> kNumParallelMerges = NumThreads / L;</div>
<div class="line"><a name="l00228"></a><span class="lineno">  228</span>&#160;    constexpr <span class="keywordtype">int</span> kNumIterations = N / kNumParallelMerges;</div>
<div class="line"><a name="l00229"></a><span class="lineno">  229</span>&#160;</div>
<div class="line"><a name="l00230"></a><span class="lineno">  230</span>&#160;    static_assert(L &lt;= NumThreads, <span class="stringliteral">&quot;list must be &lt;= NumThreads&quot;</span>);</div>
<div class="line"><a name="l00231"></a><span class="lineno">  231</span>&#160;    static_assert((N &lt; kNumParallelMerges) ||</div>
<div class="line"><a name="l00232"></a><span class="lineno">  232</span>&#160;                  (kNumIterations * kNumParallelMerges == N),</div>
<div class="line"><a name="l00233"></a><span class="lineno">  233</span>&#160;                  <span class="stringliteral">&quot;improper selection of N and L&quot;</span>);</div>
<div class="line"><a name="l00234"></a><span class="lineno">  234</span>&#160;</div>
<div class="line"><a name="l00235"></a><span class="lineno">  235</span>&#160;    <span class="keywordflow">if</span> (N &lt; kNumParallelMerges) {</div>
<div class="line"><a name="l00236"></a><span class="lineno">  236</span>&#160;      <span class="comment">// We only need L threads per each list to perform the merge</span></div>
<div class="line"><a name="l00237"></a><span class="lineno">  237</span>&#160;      blockMergeSmall&lt;NumThreads, K, V, N, L, false, Dir, Comp, FullMerge&gt;(</div>
<div class="line"><a name="l00238"></a><span class="lineno">  238</span>&#160;        listK, listV);</div>
<div class="line"><a name="l00239"></a><span class="lineno">  239</span>&#160;    } <span class="keywordflow">else</span> {</div>
<div class="line"><a name="l00240"></a><span class="lineno">  240</span>&#160;      <span class="comment">// All threads participate</span></div>
<div class="line"><a name="l00241"></a><span class="lineno">  241</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00242"></a><span class="lineno">  242</span>&#160;<span class="preprocessor"></span>      <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i &lt; kNumIterations; ++i) {</div>
<div class="line"><a name="l00243"></a><span class="lineno">  243</span>&#160;        <span class="keywordtype">int</span> start = i * kNumParallelMerges * 2 * L;</div>
<div class="line"><a name="l00244"></a><span class="lineno">  244</span>&#160;</div>
<div class="line"><a name="l00245"></a><span class="lineno">  245</span>&#160;        blockMergeSmall&lt;NumThreads, K, V, N, L, true, Dir, Comp, FullMerge&gt;(</div>
<div class="line"><a name="l00246"></a><span class="lineno">  246</span>&#160;          listK + start, listV + start);</div>
<div class="line"><a name="l00247"></a><span class="lineno">  247</span>&#160;      }</div>
<div class="line"><a name="l00248"></a><span class="lineno">  248</span>&#160;    }</div>
<div class="line"><a name="l00249"></a><span class="lineno">  249</span>&#160;  }</div>
<div class="line"><a name="l00250"></a><span class="lineno">  250</span>&#160;};</div>
<div class="line"><a name="l00251"></a><span class="lineno">  251</span>&#160;<span class="comment"></span></div>
<div class="line"><a name="l00252"></a><span class="lineno">  252</span>&#160;<span class="comment">/// Merging lists larger than a block</span></div>
<div class="line"><a name="l00253"></a><span class="lineno">  253</span>&#160;<span class="comment"></span><span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00254"></a><span class="lineno">  254</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00255"></a><span class="lineno">  255</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00256"></a><span class="lineno">  256</span>&#160;          <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00257"></a><span class="lineno">  257</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00258"></a><span class="lineno">  258</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00259"></a><span class="lineno">  259</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00260"></a><span class="lineno">  260</span>&#160;          <span class="keywordtype">bool</span> FullMerge&gt;</div>
<div class="line"><a name="l00261"></a><span class="lineno"><a class="line" href="structfaiss_1_1gpu_1_1BlockMerge_3_01NumThreads_00_01K_00_01V_00_01N_00_01L_00_01Dir_00_01Comp_00_01false_00_01FullMerge_01_4.html">  261</a></span>&#160;<span class="keyword">struct </span><a class="code" href="structfaiss_1_1gpu_1_1BlockMerge.html">BlockMerge</a>&lt;NumThreads, K, V, N, L, Dir, Comp, false, FullMerge&gt; {</div>
<div class="line"><a name="l00262"></a><span class="lineno">  262</span>&#160;  <span class="keyword">static</span> <span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> merge(K* listK, V* listV) {</div>
<div class="line"><a name="l00263"></a><span class="lineno">  263</span>&#160;    <span class="comment">// Each pair of lists is merged sequentially</span></div>
<div class="line"><a name="l00264"></a><span class="lineno">  264</span>&#160;<span class="preprocessor">#pragma unroll</span></div>
<div class="line"><a name="l00265"></a><span class="lineno">  265</span>&#160;<span class="preprocessor"></span>    <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i &lt; N; ++i) {</div>
<div class="line"><a name="l00266"></a><span class="lineno">  266</span>&#160;      <span class="keywordtype">int</span> start = i * 2 * L;</div>
<div class="line"><a name="l00267"></a><span class="lineno">  267</span>&#160;</div>
<div class="line"><a name="l00268"></a><span class="lineno">  268</span>&#160;      blockMergeLarge&lt;NumThreads, K, V, L, Dir, Comp, FullMerge&gt;(</div>
<div class="line"><a name="l00269"></a><span class="lineno">  269</span>&#160;        listK + start, listV + start);</div>
<div class="line"><a name="l00270"></a><span class="lineno">  270</span>&#160;    }</div>
<div class="line"><a name="l00271"></a><span class="lineno">  271</span>&#160;  }</div>
<div class="line"><a name="l00272"></a><span class="lineno">  272</span>&#160;};</div>
<div class="line"><a name="l00273"></a><span class="lineno">  273</span>&#160;</div>
<div class="line"><a name="l00274"></a><span class="lineno">  274</span>&#160;<span class="keyword">template</span> &lt;<span class="keywordtype">int</span> NumThreads,</div>
<div class="line"><a name="l00275"></a><span class="lineno">  275</span>&#160;          <span class="keyword">typename</span> K,</div>
<div class="line"><a name="l00276"></a><span class="lineno">  276</span>&#160;          <span class="keyword">typename</span> V,</div>
<div class="line"><a name="l00277"></a><span class="lineno">  277</span>&#160;          <span class="keywordtype">int</span> N,</div>
<div class="line"><a name="l00278"></a><span class="lineno">  278</span>&#160;          <span class="keywordtype">int</span> L,</div>
<div class="line"><a name="l00279"></a><span class="lineno">  279</span>&#160;          <span class="keywordtype">bool</span> Dir,</div>
<div class="line"><a name="l00280"></a><span class="lineno">  280</span>&#160;          <span class="keyword">typename</span> Comp,</div>
<div class="line"><a name="l00281"></a><span class="lineno">  281</span>&#160;          <span class="keywordtype">bool</span> FullMerge = <span class="keyword">true</span>&gt;</div>
<div class="line"><a name="l00282"></a><span class="lineno">  282</span>&#160;<span class="keyword">inline</span> __device__ <span class="keywordtype">void</span> blockMerge(K* listK, V* listV) {</div>
<div class="line"><a name="l00283"></a><span class="lineno">  283</span>&#160;  constexpr <span class="keywordtype">bool</span> kSmallerThanBlock = (L &lt;= NumThreads);</div>
<div class="line"><a name="l00284"></a><span class="lineno">  284</span>&#160;</div>
<div class="line"><a name="l00285"></a><span class="lineno">  285</span>&#160;  <a class="code" href="structfaiss_1_1gpu_1_1BlockMerge.html">BlockMerge&lt;NumThreads, K, V, N, L, Dir, Comp, kSmallerThanBlock, FullMerge&gt;::</a></div>
<div class="line"><a name="l00286"></a><span class="lineno">  286</span>&#160;<a class="code" href="structfaiss_1_1gpu_1_1BlockMerge.html">    merge</a>(listK, listV);</div>
<div class="line"><a name="l00287"></a><span class="lineno">  287</span>&#160;}</div>
<div class="line"><a name="l00288"></a><span class="lineno">  288</span>&#160;</div>
<div class="line"><a name="l00289"></a><span class="lineno">  289</span>&#160;} } <span class="comment">// namespace</span></div>
<div class="ttc" id="structfaiss_1_1gpu_1_1BlockMerge_html"><div class="ttname"><a href="structfaiss_1_1gpu_1_1BlockMerge.html">faiss::gpu::BlockMerge</a></div><div class="ttdef"><b>Definition:</b> <a href="MergeNetworkBlock_8cuh_source.html#l00213">MergeNetworkBlock.cuh:213</a></div></div>
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